Fluorescent whitening agents (FWAs), also known as optical brighteners, have long been used in a wide variety of commercial applications such as paper, textiles, inks, coatings and plastics. By absorbing non-visible light in the UV range, then emitting the absorbed energy as visible light, notably visible blue light, FWAs provide a brighter appearance to materials into which they are formulated. For example, FWAs are used to camouflage a yellow or dingy color and create a whiter appearance in many paper and fabric applications and can mask slight discoloration in clear polymeric articles, for example clear polycarbonate.
Fluorescent whitening agents are also used to provide a brighter or more vibrant appearance to dyed and pigmented articles, as in textile, ink, coating and printing applications. Use in soaps, cosmetics and other personal care applications is also common.
Due to their ability to absorb light, particularly UV light, FWAs of sufficient permanence can also be useful as light screeners protecting both the material in which they are formulated as well as any light sensitive material deployed beneath, such as such as lower layers in a laminate, contents of a plastic bottle or even the skin under a clothing fabric into which a FWA has been incorporated. Certain FWAs, such as those of the present invention, can also slow light induced degradation by quenching the excited states generated upon light absorption of, for example, dyes and pigments.
FWAs have also found use in security printing, in bio- and chemical sensors and as markers allowing for the ready detection of defects in the manufacture and repair of a variety of articles including coated articles, electronic materials and even basic consumer products.
U.S. Pat. No. 5,976,410 discloses FWA dispersions used in coating paper or paper fibers in the pulp during paper production.
U.S. Pat. No. 5,308,545 discloses pyrazoline FWAs and their use in treating fabrics of natural, e.g., cellulose acetate, and synthetic fibers, e.g., acrylic, nylon. U.S. Pat. No. 5,779, 741 discloses a method for the fluorescent whitening of cotton.
U.S. Pat. No. 6,635,320 discloses the use of FWAs in an ink jet recording sheet as both Ultra Violet absorber and optical brightener. U.S. Pat. No. 6,136,420 discloses laminated polyester film, useful as receiving media in printing, containing FWAs or FWAs and pigments.
U.S. Pat. Nos. 6,054,021 and 6,174,586 disclose the use of FWAs in security paper.
U.S. Pat. No. 5,714,121 discloses the use of FWAs in carbon dioxide sensors.
U.S. Pat. No. 5,976,410 discloses the use of fluorescent flavanoid derivatives in the production of easily inspected circuit boards and U.S. Pat. No. 4,969,350 discloses a method for inspecting tires for defects using solutions of commercially available FWAs.
Pending U.S. application Ser. No. 10/519,031, filed Jun. 23, 2006, discloses triazinylaminostilbene disulfonic acid mixtures, their use as FWAs in paper and textiles, and their use in fabrics to protect skin from UV radiation.
The above patents and application, and the references therein, are hereby incorporated in their entirety by reference.
A light absorbing para-terphenyl derivative (i.e., [4,3j]quinophenanthrine-6,13-dione) rendered rigid by the introduction of 2 fused lactam bridges linking the three phenyl rings is disclosed by Lamba and Tour, J. Am. Chem. Soc., 1991, 116, 11723-11736.